Tortonian fish otoliths from turbiditic deposits in Northern Italy: Taxonomic and stratigraphic significance

Abstract

Fish otoliths from the fossiliferous turbiditic sand deposits outcropping at the Borelli and Moncucco localities (Piedmont, Northern Italy) are herein analyzed. The studied section is Tortonian in age and belongs to the lower portion of the Sant'Agata Fossili Formation. The study reveals the presence of at least 90 otolith-based taxa of which 78 are identified at the species level. Two of these are named and described as new species: "Gobiida" bicornuta and "Gobiida" brioche. In addition, 19 taxa, including both still living and extinct ones, are recorded for the first time in Tortonian deposits. Among them, the still living Nansenia aff. oblita, ?Sagamichthys schnakenbecki, and Chaunax pictus are found as fossils for the first time. The high diversity of this well-preserved otolith assemblage improves the systematic knowledge of the Tortonian gobiids and other neritic taxa, which show a close affinity with the present-day Mediterranean fauna. Moreover, the stratigraphic distribution of both neritic and mesopelagic taxa, that were previously considered to enter the Mediterranean Basin in younger stratigraphic intervals, can now be extended back to the Tortonia

Tortonian teleost otoliths from northern Italy: taxonomic synthesis and stratigraphic significance

“…In this approach, species that can only be allocated at family level (or higher-ranking level), but not attributed to a precise Recent genus, are designated by the type genus of the concerned family (or subfamily, etc. ), between inverted commas, instead of the open generic nomenclature applied in Nolf (2013), in which the generic designations are not genera in the sence of the ICZN Code, e.g., "Gobiida" bicornuta Lin et al, 2015 is converted to "Gobius" bicornutus (Lin et al, 2015), where "Gobius" stands for an incertae sedis gobiid. For reasons of logical consistency within the present paper, all species that were previously described in open generic nomenclature have been converted to the system required by the ICZN Code for use in our text, plus Tables 1 and 2.…”

“…2, figs 1-4), the specimens in question are all assigned to X. senesi. The studied material, including large and small specimens, allows us to refer the otoliths figured by Lin et al (2015: fig. 2(5), as Xenodermichthys aff.…”

“…This fauna is also characterised by a high number of modern genera, grouping both extant and fossil species (Lin et al 2015) The present study emphasises a taxonomic revision by integrating newly acquired material with previously published results, and aims to reconstruct a complete survey of the Tortonian otolithbased fish fauna in this region. A list of updated nominal species is compiled and their stratigraphical and geographical distribution is discussed.…”

“…In northern Italy, Tortonian deposits yielding fish otolith are known and have been studied for more than a century (Bassoli 1906;Anfossi & Mosna 1969a, 1969bRobba 1970;Anfossi & Mosna 1971;Nolf & Steurbaut 1983;Girone et al 2010;Lin et al 2015;Lin 2016), revealing an otolith-based fish fauna of about 100 taxa. The fauna from this area thus became the best known in the Mediterranean Basin.…”

“…The otolith-bearing deposits are mainly hemipelagic marls and attain more than 100 metres of thickness at many places. Additional material from the turbiditic Tortonian deposits intercalated in the hemipelagic marls was reported in Lin et al (2015).…”